I'm doing my dino gear oil change for the year and I don't have a lot of money to drop on 7 quarts of a quality synthetic. I had a differential leak so was using thick Lucas oil (yes I know). I have that fixed up so now I want to put a thinner gear oil back in. I know that Rotella is good and cheap at Walmart and figure that is a best buy for a budget gear oil. Any opinions on coastal or supertech?